In a medical imaging system, such as a low-cost CT scanner, low-cost components must be efficiently used to ensure that the medical imaging instrument will be affordable. However, the accuracy and stability of the low-cost components can be unacceptable. For example, commonly encountered environmental conditions can adversely affect the accuracy and stability of the various components of a CT scanner. To compensate for these effects, measurements must be made of various system operational parameters and conditions for system monitoring, and system diagnostic conditions for system testing and debugging. Further, the measurements must be made on a real-time basis.
For example, the measurements of system operational and system diagnostic parameters and conditions that can advantageously be made include:
measurements of the temperature of various subsystems; PA1 measurements of the position of the x-ray tube focal spot; PA1 measurements of vibrational motion of the x-ray tube; PA1 measurements of the voltage of various electrical subsystems; and PA1 measurements of the electrical current of various electrical subsystems.
It is known to provide one or more separate measuring systems for performing each type of measurement, each measuring system being connected to a main computer of the medical imaging system via an information signal transmission channel having a separate A/D converter and separate cabling. This approach can be expensive, can add excessive weight and complexity to the medical imaging system, and can occupy large amounts of space.
To avoid separate dedicated cabling, it is known to deliver system monitoring and system diagnostic measurement information to the main computer via a data acquisition system (DAS), where the DAS conveys primarily image data to the main computer. In particular, the DAS accommodates a plurality of information signal transmission channels, each channel conveying data encoded as a stream of data words. However, the DAS can accommodate only a limited number of channels for conveying non-image data. Each type of non-image data typically requires at least one DAS channel, and there can be several times more types of measurements needed for proper characterization of the subsystems of the CT scanner than the number of available non-image DAS channels.